Surface treatment of glass containers

Abstract

A method for treating hot glass containers that are moved through a treatment zone. The treatment zone is a system which utilizes heated compressed air aspirators rather than electric motor driven blowers to cause a treatment vapor laden air contained in chambers to be propelled across the width of the ware conveyor from both sides at adjacent, horizontally spaced, points in the conveyor length. The resultant streams of heated air and vapor laden air will impinge on the containers carried on the conveyor and are of a size to cover the container height to about the shoulder. The vapor and air that passes the containers from one direction is captured and fed to the chamber for feeding in the other direction. Thus the vapor laden air is recirculated from side to side with additional concentrated treatment vapors introduced to maintain a certain level of tin or titanium in the vapors so as to produce the metal oxide coating on the containers. In addition, streams of air propelled by heated compressed air aspirators rather than motor driven blowers sweep across the finish portion of the container immediately above the vapor laden streams to effectively keep the metal oxide coating from forming on the threads or finish of the container.

What is claimed: 
     
       1. The method of forming a metal oxide coating on the exterior of glass containers having a body portion and upper, finish portion while moving in succession on a conveyor through a treatment zone, comprising the steps of creating a first generally horizontal flow path of compressed air directed across the width of the conveyor in one direction, said flow being narrow in width and height dimension, surrounding said first flow path with a first tapering chamber having a narrowing outlet, said first chamber being of a larger size than the first flow path, introducing a metal halide treatment vapor into the tapering chamber and propelling the vapor across the width of the conveyor with the directed flow of heated compressed air, collecting the vapor containing air flow on the opposite side, creating a second horizontal flow path of compressed air across the conveyor at a second position, surrounding said second flow path with a second tapering chamber, having a narrowing outlet, said second chamber being larger than the second flow path, introducing the vapor containing air collected from said first flow path into the second tapering chamber and propelling the vapor in said second chamber by said second flow path, collecting the vapor containing flow from said second flow path and introducing it to the inlet to the first tapering chamber with the addition of treatment vapor whereby the vapor and air are circulated and recirculated across the width of the conveyor to treat the body portion of containers passing through the vapor and creating a flow of compressed air across the upper finish portion of the containers, in parallel to the first and second flow paths to prevent treatment reaching the finish. 
     
     
       2. In the method of forming a metal oxide coating on the body portion of newly formed glass containers moving upright in succession on a conveyor prior to their passage into an annealing lehr, wherein a metallic halide in vapor form is propelled from chambers across the conveyor width in two streams from both sides of the conveyor at adjacent, horizontally spaced points in the conveyor length, said streams having a height comparable to the height of the side wall and shoulder area of the container and wherein the treatment vapor is continuously circulated from one stream to the other across the conveyor in a closed loop and with an air barrier also being provided across the finish of the containers just above the moving streams of the metallic halide vapor, the improvement comprising propelling the metallic halide vapor by the injection of heated compressed air into the vapor in the chambers to create the flow of metallic halide vapor across the conveyor and injecting heated compressed air in the direction of the finish of the containers to create a flow of heated air as a barrier across the finish of the containers being coated. 
     
     
       3. The method of claim 2 further comprising heating the compressed air to a temperature of 300°-800° F. before injecting it into the chambers containing the metallic halide vapor and before creating the air barrier flow. 
     
     
       4. The method of claim 3 wherein said compressed air is heated to 350°-500° F. at the point of injection into the vapor and the creation of the air streams. 
     
     
       5. The method of claim 3 wherein the heating of the compressed air is done by passing the air through a heat exchanger positioned in the annealing lehr prior to introduction to the treatment chambers.